06-29-2002
When you want to exceed the maximum value of the largest data type that a language has, you have a clear path to follow: invent your own data type. You will need to write routines to convert long double to and from your private data type. You will need to write your own routines to add to elements of your private data type. And you will need to write your own routines to display the values of your private data type.
The bad news: none of this is easy and it probably cannot be written portably. The good news: your private data type can take many forms, so there are indeed a lot of solutions.
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LEARN ABOUT DEBIAN
pgpverify
pgpverify(8) System Manager's Manual pgpverify(8)
NAME
pgpverify - cryptographically verify Usenet control messages
SYNOPSIS
pgpverify
DESCRIPTION
The pgpverify program reads (on standard input) a Usenet control message that has been cryptographically signed using the signcontrol pro-
gram. pgpverify then uses the pgp program to determine who signed the control message. If the control message was validly signed, pgpver-
ify outputs (to stdout) the User ID of the key ID that signed the message.
OPTIONS
The pgpverify program takes no options.
EXIT STATUS
pgpverify returns the follow exit statuses for the following cases:
0 The control message had a good PGP signature.
1 The control message had no PGP signature.
2 The control message had an unknown PGP signature.
3 The control message had a bad PGP signature.
255 A problem occurred not directly related to PGP analysis of signature.
AUTHOR
David C Lawrence <tale@isc.org>
ENVIRONMENT
pgpverify does not modify or otherwise alter the environment before invoking the pgp program. It is the responsibility of the person who
installs pgpverify to ensure that when pgp runs, it has the ability to locate and read a PGP key file that contains the PGP public keys for
the appropriate Usenet hierarchy administrators.
SEE ALSO
pgp(1)
NOTES
Historically, Usenet news server administrators have configured their news servers to automatically honor Usenet control messages based on
the originator of the control messages and the hierarchies for which the control messages applied. For example, in the past, David C
Lawrence <tale@uunet.uu.net> always issued control messages for the "Big 8" hierarchies (comp, humanities, misc, news, rec, sci, soc,
talk). Usenet news administrators would configure their news server software to automatically honor newgroup and rmgroup control messages
that originated from David Lawrence and applied to any of the Big 8 hierarchies.
Unfortunately, Usenet news articles (including control messages) are notoriously easy to forge. Soon, malicious users realized they could
create or remove (at least temporarily) any Big 8 newsgroup they wanted by simply forging an appropriate control message in David
Lawrence's name. As Usenet became more widely used, forgeries became more common.
The pgpverify program was designed to allow Usenet news administrators to configure their servers to cryptographically verify control mes-
sages before automatically acting on them. Under the pgpverify system, a Usenet hierarchy maintainer creates a PGP public/private key pair
and disseminates the public key. Whenever the hierarchy maintainer issues a control message, he uses the signcontrol program to sign the
control message with the PGP private key. Usenet news administrators configure their news servers to run the pgpverify program on the
appropriate control messages, and take action based on the PGP key User ID that signed the control message, not the name and address that
appear in the control message's From or Sender headers.
Thus, using the signcontrol and pgpverify programs appropriately essentially eliminates the possibility of malicious users forging Usenet
control messages that sites will act upon, as such users would have to obtain the PGP private key in order to forge a control message that
would pass the cryptographic verification step. If the hierarchy administrators properly protect their PGP private keys, the only way a
malicious user could forge a validly-signed control message would be by breaking the RSA encryption algorithm, which (at least at this
time) is believed to be an NP-complete problem. If this is indeed the case, discovering the PGP private key based on the PGP public key is
computationally impossible for PGP keys of a sufficient bit length.
<URL:ftp://ftp.isc.org/pub/pgpcontrol/> is where the most recent versions of signcontrol and pgpverify live, along with PGP public keys
used for hierarchy administration.
pgpverify(8)